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A187042
Numbers the expansion of which over distinct terms of A050376 contains the same number of primes and perfect squares.
2
8, 12, 18, 20, 27, 28, 32, 44, 45, 48, 50, 52, 63, 68, 75, 76, 80, 92, 98, 99, 112, 116, 117, 124, 125, 147, 148, 153, 162, 164, 171, 172, 175, 176, 188, 207, 208, 212, 216, 236, 242, 243, 244, 245, 261, 268, 272, 275, 279, 284, 292, 304, 316, 325, 332, 333, 338
OFFSET
1,1
COMMENTS
The sequence does not contain squarefree numbers or perfect squares.
LINKS
EXAMPLE
147 and 216 are in the sequence, since their expansions over distinct terms of A050376 are 3*49 and 2*3*4*9 respectively. Thus the expansion of 147 contains one prime and one perfect square, while the expansion of 216 contains two primes and two perfect squares.
MATHEMATICA
aQ[n_] := Total @ (d = IntegerDigits[Last /@ FactorInteger[n], 2])[[;; , -1]] == Total @ Flatten @d / 2; Select[Range[350], aQ] (* Amiram Eldar, Oct 01 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Mar 02 2011
EXTENSIONS
a(28)=153 inserted and more terms added by Amiram Eldar, Oct 01 2019
STATUS
approved